It is previously known in this art to employ two mutually displaceable masses or bodies for the purpose of reducing the vibrations generated in a tool. Examples of such prior-art technology are revealed in Swedish patent No. 7603252-3.
To some extent, such prior-art solutions have resulted in reduced vibrations at low loads, but the vibrations increase with greater loads. Moreover, such prior-art solutions suffer from the drawback that they consume unnecessarily large amounts of drive medium, partly because only the one moving part carries out useful work during its displacement, and partly because the drive medium is continually applied between the moving parts. While another prior-art solution, disclosed in Swedish patent No. 8204044-5, shows a supply valve, this valve is only shut off in conjunction with the one limit position, a certain reduction in the air consumption being hereby obtained as compared with the chisel device according to the first-mentioned Swedish patent. A further drawback inherent in the above-mentioned prior-art types of apparatus is that they are difficult to "creep-start" and that they undergo a major change in operational mode on contact with the workpiece which is to be processed, for instance the vibration level changes on impacts of varying power by the apparatus against the workpiece. In addition, the prior-art types of apparatus suffer from difficulties in providing the necessary stroke lengths and kinetic energies for specific requirements.